After finishing her morning journal, Emily decides to proceed without Wendell, who has not returned despite claiming he would accompany her. She sends Henry and Lizzie to investigate volcanic features, then visits the blue house alone. The house answers her knocking with unnatural screams and cold, but outside she meets Mord Samson and realizes the family is not dealing with a wight at all: their son Ari was stolen five winters earlier, when he was already about a year old, and a changeling was left behind. Mord explains that he and his wife Aslaug live under constant cold and relentless torment, and Emily’s scientific interest sharpens because both the child’s age and the changeling’s behavior seem unusual.

Inside the house, Emily notes the ordinary rooms and the family’s exhausted endurance. When she approaches the attic, the stairs transform into wolf-maws under illusion, but Emily sees through the glamour by turning her coat inside out. In the attic she finds a strikingly beautiful, intelligent changeling, far different from the brutish creatures described in most accounts. The changeling threatens to intensify Mord and Aslaug’s suffering, and Emily tries salt before turning to iron. With Shadow’s help, Emily wounds the changeling with an iron nail, forcing it partly out of its mortal guise, and then uses Ari’s coat as leverage because mortal clothing strengthens faeries and helps sustain their human form.

Emily questions the changeling for about an hour, but the answers are frustratingly limited. The child-faerie mostly complains about missing its forest, its willow tree, and its family, and either cannot or will not explain why it was sent to Hrafnsvik. Emily eventually returns the coat and leaves, giving Mord and Aslaug the practical advice of wearing clothing inside out to weaken the hold of the visions. When Aslaug returns from her daily walk, Emily sees how physically and mentally depleted she has become. Emily wants to help the couple, but she has no clear way to free them without endangering the stolen child.

Back at the empty cottage, Emily goes to the spring to see the brownie she privately calls Poe. After washing for the first time since arriving in Hrafnsvik and waiting with chocolates, Emily learns that Wendell has already visited. Poe says Wendell was kind, even bringing peppermints, but the brownie is frightened because Wendell is not merely one of the Folk but a prince, one of the dangerous high ones. Poe also reveals that Wendell was asking about doors into Faerie. Poe claims there are no such doors in that forest now, though they may move with the snows and the approach of the high ones. This revelation confirms Emily’s suspicion that Wendell is fae nobility and makes his motives feel far more alarming.

Needing time to think, Emily surveys the woods and notices signs of possibly shifting faerie features before finding Wendell asleep in a clearing. She confronts him for interfering with her brownie and for idling while she works, and Wendell replies that he has actually spent the day exploring and found a high mountain lake with signs of kelpie habitation. Emily tells him about the changeling and Mord and Aslaug’s suffering, and Wendell reacts with cool detachment, arguing that killing or driving off the changeling would also kill the stolen child and that scholars are meant to observe rather than interfere. Emily presses him anyway, partly testing what he may be capable of, and Wendell finally agrees to visit the Samsons the next day before returning with her to the cottage.